The U.S.-Korea Institute at Johns Hopkins University reported today that North Korea may be making good on promises to develop nuclear arms, by producing fuel rods necessary for a plutonium reactor and, therefore, to operate nuclear facilities. According to the institute, this marks a major development in the hermit nation's quest for nuclear weapons:

Commercial satellite imagery has identified facilities at the Yongbyon Nuclear Scientific Research Center that may produce fuel for North Korea’s recently restarted 5 MW plutonium production reactor and the Experimental Light Water Reactor (ELWR) still under construction. The identification of these facilities indicates a more wide-ranging, extensive effort by North Korea to modernize and restart the Yongbyon complex dating back to 2009 than previously understood.

Analysts at the institute examined satellite imagery to determine that two buildings are likely actively fabricating and assembling fuel rods. According to the institute, one building probably producing fuel rods was designed for that purpose in the early 1980s, before falling into disrepair. North Korea began cleaning up the facility in 2009, and the experts believe it is being used for fuel production again because satellite images show soot on the facility's roof, indicating "that a heating process had occurred, such as the use of metal casting furnaces necessary to complete the heat treatment during the fuel rod assembly." Furthermore, the images show a white stain on the roof, which "may be the result of chemical vapors or gases being released. For example, the hydrofluoric acid used to produce the fuel rods is acidic enough to cause this bleaching effect."

The institute also suspects that one of the largest structures in North Korea's Yongbyon nuclear complex could be used to produce light water reactor fuel assemblies - a process which would take two to three years.

North Korea reopened its nuclear facilities over the summer, after they had been shuttered for six years. According to The New York Times, the country currently has an estimated 2,000 fuel rods, roughly 6,000 short of the amount needed for the plant to produce plutonium. The volatile country's nuclear ambitions are a cause of concern for global leaders, especially following leader Kim Jong-un's brutal and unorthodox execution of his uncle.

South Korea is especially vulnerable to a nuclear threat, because of its proximity to the North and because the countries are still technically at war, as the truce that ended the Korean War in 1953 is classified a cease-fire. Just last week North Korea threatened South Korea with "a merciless retaliation without warning," albeit via fax. But the oft-repeated threat becomes less amusing as the country takes tangible step towards nuclear capability.

Efforts at nuclear negotiation with Pyongyang effectively stalled in 2008, when six-nation talks between North Korea, South Korea, the U.S., China, Japan and Russia over the DPRK's nuclear program broke down. Though North Korea said recently that it would consider restarting negotiations, the U.S. and others say they will not participate, preferring to press forward with economic sanctions against Pyongyang. North Korea's February nuclear test, the country's latest and third in seven years, prompted a tightening of sanctions by the U.S. and a series of outsize threats by Pyongyang against Washington and Seoul. The not-quite-credible-crisis was ultimately averted, and may have been part of a pro-government propaganda campaign leading up to the celebration of the Kim dynasty.

This article is from the archive of our partner The Wire.

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Danielle Wiener-Bronner is a former staff writer for The Wire. Her work has appeared in The Huffington Post and Reuters.